(a) Field of the Invention
The present invention relates to a reflecting mirror to be used in image pickup systems of photographic cameras, electronic still cameras and so on.
(b) Field of the Invention
As one of the optical systems to be used in instant cameras and half-size cameras, there is already known the optical system, for example, shown in FIG. 1 wherein a first reflecting mirror 2 and a second reflecting mirror 3 are arranged in the vicinity of an image forming surface 4 for leading a light bundle from an imaging lens 1 to the image forming surface 4. In such an optical system, the second reflecting mirror 3 is so designed as to have a surface size just required for reflecting an effective light bundle or a surface size larger than the diameter of the effective light bundle with unnecessary marginal area shielded by a black paint or by a portion of a fixing frame as shown in FIG. 2A. Accordingly, when a portion of the light diffusedly reflected from an image of an object formed on the image forming surface 4 due to the diffusing property of the image forming surface 4 is incident, as the veiling glare, again on the image forming surface 4 from the reflecting mirror 3, the veiling glare 5 is partitioned on the image forming surface 4 along a boundary 5a corresponding to the outer circumference of the above-mentioned shielding member or the reflecting mirror 3 as shown in FIG. 2B. Since the human eyes have a high capability to detect such a boundary due to the visual characteristic inherent therein, the partition is distinguishable enough to make unappreciated the pictures photographed with such an optical system even when intensity of light sources is not so high and the above-mentioned veiling glare is no so remarkable.